The invention relates to a snow plow or snow shovelling apparatus and more particularly to an unmotorized manually operated apparatus which allows the lifting and discharging of snow therefrom with minimal physical exertion on the part of the user.
As is well known, the repeated bending over and lifting necessitated by the normal snow shovelling operation puts considerable strain on the spine, ligaments and muscles associated therewith. For this reason, shovelling of snow from a person's sidewalks can result in back aches, back muscle strains and sprains and generally the generally be an unpleasant experience. In addition, the leverage involved in holding a heavy load of snow at a distance from the shoveller's torso can put guite a burden on the heart muscle as well as the back generally. Thus, the activity of shovelling snow can be very heavy exertion for a person who may already be tired after having put in a full day's work and can therefore be very exhausting as well as subject the shoveller to a very real risk of injury to the heart, back or other parts of the body.
Prior art devices for shovelling snow characteristically incorporate some type of leverage to allow manual lifting of snow and/or flipping of snow from the device. Some of these devices require the user to twist or turn a handle in order to rotate the snow scoop and flip the snow from the scoop. An example of such a device is disclosed in U.S. Pat. No. 2,441,449 to Shaw. The Shaw device requires that the user bear down on the handle with his weight thereon in order to lift the snow carried in the scoop. The handle and scoop are mounted on a frame which pivots on a fulcrum structure (based on the wheel axis) during this lifting operation. The handles are turned about a second axis disposed intermediate the wheels to dump the snow to a side of the device by a sort of flipping action. The primary disadvantage with this prior art device is that the entire lifting and flipping operation requires substantial physical exertion on the part of the user. Moreover, in order to flip the snow a substantial distance from the sidewalk and thereby ensure that the snow does not pile up adjacent the sidewalk where it can slide thereunto later (requiring the user to clear the same area over again), the user must put more power into the flipping motion in order to increase the flipping speed and thereby "throw" the snow a greater distance. Thus, the heavy physical exertion involved in the use of such a prior art device may also result in the same type and severity of injury as less highly leveraged shovelling devices such as a regular snow shovel.
Another prior art device, disclosed in U.S. Pat. No. 2,720,043 to Chamberlin, for shovelling snow from walkways uses a complicated set of levers and oscillating rods linked to a snow scoop and a handle. Pushing down on a handle tilts the scoop and throws the snow from the scoop. However, due to the complex linkage system much of the user's energy expended in tilting the scoop by moving the handle is wasted because of binding of the linkage and frictional losses. Therefore, it is very difficult for the user to "throw" the snow a very long distance. Thus, as with the previous prior art device, the Chamberlin device cannot put the snow a sufficient distance from the walkway to in effect clear the walkway and does not siginificantly reduce the amouunt of physical energy required of the user. In addition, the complexity of such systems makes them more trouble prone and inefficient.
Other prior art snow plow devices use both leverage and body weight to shovel the snow. An example of such a plow is disclosed in U.S. Pat. No. 3,107,446 to Messinger. In this prior art plow, the handle is adjustable in order to accommodate the height of the user and to add more leverage to move a greater quantity of snow. The scoop is balanced on an axis so that when the scoop is filled with snow and unlatched from its rear attachment to the frame, the weight of the snow causes the scoop to tilt and dump the snow. However, the scoop must be moved to a place where the snow is to be dumped because the device has no capability of "throwing" the snow load. Thus, the device requires the user to expend a lot of energy in order to move the device around. In addition, the device requires the user to have a certain degree of strength and to expend considerable energy to lift the snow. Thus, use of the device involves considerable physical exertion and the user is consequently subject to the same risks of physical injury as with the use of the prior art devices previously discussed.
Powered prior art devices relieve the user of the physical exertion otherwise required to shovel snow from a walkway. These devices which include snow blowers and motorized snow plows require the same relatively high maintenace as other motorized vehicles and equipment. Additionally, such motorized devices may be very troublesome in that they may be very difficult to start after months of disuse. Moreover, many motorized devices are typically hard to start in cold weather. Fuel costs added to the maintenance costs and troublesome operation may not outweigh the saving in physical work such devices provide. Consequently, although such motorized prior art devices provide desired benefits, they have many disadvantages precluding them from having widespread appeal to members of the public which have a need for snow plows.
Thus, a snow plow is needed that has low maintenance costs, is energy efficient, and can eject snow well away from the walkway in order to properly clear the walkway. Moreover, a snow plow is needed that has such attributes while being capable of plowing snow with a minimum of physical exertion required from the user.